microblaze: Add libgcc function directly to kernel

Replaced libgcc functions with asm optimized implementation.

Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/lib/udivsi3.S

@@ -0,0 +1,84 @@
+#include <linux/linkage.h>
+
+/*
+* Unsigned divide operation.
+*	Input :	Divisor in Reg r5
+*		Dividend in Reg r6
+*	Output: Result in Reg r3
+*/
+
+	.text
+	.globl	__udivsi3
+	.type __udivsi3, @function
+	.ent __udivsi3
+
+__udivsi3:
+
+	.frame	r1, 0, r15
+
+	addik	r1, r1, -12
+	swi	r29, r1, 0
+	swi	r30, r1, 4
+	swi	r31, r1, 8
+
+	beqi	r6, div_by_zero /* div_by_zero /* division error */
+	beqid	r5, result_is_zero /* result is zero */
+	addik	r30, r0, 0 /* clear mod */
+	addik	r29, r0, 32 /* initialize the loop count */
+
+/* check if r6 and r5 are equal - if yes, return 1 */
+	rsub	r18, r5, r6
+	beqid	r18, return_here
+	addik	r3, r0, 1
+
+/* check if (uns)r6 is greater than (uns)r5. in that case, just return 0 */
+	xor	r18, r5, r6
+	bgeid	r18, 16
+	add	r3, r0, r0 /* we would anyways clear r3 */
+	blti	r6, return_here /* r6[bit 31 = 1] hence is greater */
+	bri	checkr6
+	rsub	r18, r6, r5 /* microblazecmp */
+	blti	r18, return_here
+
+/* if r6 [bit 31] is set, then return result as 1 */
+checkr6:
+	bgti	r6, div0
+	brid	return_here
+	addik	r3, r0, 1
+
+/* first part try to find the first '1' in the r5 */
+div0:
+	blti	r5, div2
+div1:
+	add	r5, r5, r5 /* left shift logical r5 */
+	bgtid	r5, div1
+	addik	r29, r29, -1
+div2:
+/* left shift logical r5 get the '1' into the carry */
+	add	r5, r5, r5
+	addc	r30, r30, r30 /* move that bit into the mod register */
+	rsub	r31, r6, r30 /* try to subtract (r30 a r6) */
+	blti	r31, mod_too_small
+/* move the r31 to mod since the result was positive */
+	or	r30, r0, r31
+	addik	r3, r3, 1
+mod_too_small:
+	addik	r29, r29, -1
+	beqi	r29, loop_end
+	add	r3, r3, r3 /* shift in the '1' into div */
+	bri	div2 /* div2 */
+loop_end:
+	bri	return_here
+div_by_zero:
+result_is_zero:
+	or	r3, r0, r0 /* set result to 0 */
+return_here:
+/* restore values of csrs and that of r3 and the divisor and the dividend */
+	lwi	r29, r1, 0
+	lwi	r30, r1, 4
+	lwi	r31, r1, 8
+	rtsd	r15, 8
+	addik	r1, r1, 12
+
+.size __udivsi3, . - __udivsi3
+.end __udivsi3